1. Field of the Invention
The present invention relates to an ultrasonic motor using a transducer exciting an elliptical movement produced by combining a bending standing-wave vibration with a longitudinal vibration.
2. Description of the Related Art
A linear ultrasonic motor that relatively moves a driven object by urging a transducer in contact with an elastic body, the transducer being composed of a piezoelectric element exciting an elliptical movement produced by combining a bending standing-wave vibration with a longitudinal vibration, is disclosed in Japanese Patent Publication No. 2871768 and Japanese Unexamined Patent Application Publication No. 8-182356.
A toroidal ultrasonic motor for driving a body of rotation proposed in Publication of Japanese Examined Patent Application No. 7-48087 is applicable to a lens barrel using free-traveling waves. The lens barrel includes a fixed cylinder, an ultrasonic motor composed of a stator and a range ring as a body of rotation, and a moving lens driven back and forth by the range ring.
Furthermore, a rotary ultrasonic motor disclosed in Japanese Patent Publication No. 3401097 includes a transducer exciting an ultrasonic elliptical vibration and a rotor having a shaft as the center of rotation.